Stalwart
CVE-2026-26312
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource allocation limits
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS 6.5 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this flaw, an out-of-memory condition and server crash. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Denial-of-service in Stalwart Mail Server versions 0.13.0 through 0.15.4 allows authenticated users to crash the server by sending a specially crafted email with malformed nested MIME parts through IMAP or JMAP, triggering infinite loops and resource exhaustion. The vulnerability requires valid credentials to exploit and public exploit code exists, but no patch is currently available for affected versions.
Earlier versions of this analysis (1)
Stalwart versions up to 0.15.4 is affected by allocation of resources without limits or throttling (CVSS 6.5).
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affects Stalwart. Stalwart is a mail and collaboration server. A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4 where accessing a specially crafted email containing malformed nested message/rfc822 MIME parts via IMAP or JMAP causes excessive CPU and memory consumption, potentially leading to an out-of-memory condition and server crash. The malformed structure causes the mail-parser crate to produce cyclical references in its parsed representation, which Stalwart
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
Lifecycle Timeline
2DescriptionGitHub Advisory
Stalwart is a mail and collaboration server. A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4 where accessing a specially crafted email containing malformed nested message/rfc822 MIME parts via IMAP or JMAP causes excessive CPU and memory consumption, potentially leading to an out-of-memory condition and server crash. The malformed structure causes the mail-parser crate to produce cyclical references in its parsed representation, which Stalwart then follows indefinitely. Version 0.15.5 contains a patch.
Executive ViewAI
Organizations using Stalwart Mail Server should be aware of notable risk from CVE-2026-26312 rated CVSS 6.5. Exploitation could compromise the security of affected deployments. Proof-of-concept code is publicly available. Organizations should apply vendor updates when available and monitor for exploitation.
Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Exploit-DB